In facilities where industrial gearboxes are used, equipment is often initially installed with only a minimum set of features to adhere to the basic purposes. As such, a machine is often installed without many additional accessories, some of which may enhance the life, functionality, and/or reliability of the machine. One such exemplary machine is a gear drive, such as for a dry cooling system and/or a steam condenser, in which the gear drive includes a primary oil pump for circulating oil along a primary oil circulation system to various locations of a gear box in order to lubricate portions of the gear drive. Frequently, it is desired to have an oil filter installed as part of the oil circulation system. Such oil filters may be provided as an in-line filter system or as an off-line filter system.
An off-line filter system is connected to a supply of the oil in a manner that is not directly disposed along the primary oil circulation system. Such a system frequently includes a secondary oil circulation system connected to the supply of oil and along which a filter and a secondary oil pump are operatively disposed. The oil filter and the secondary oil pump are normally located outside of the main gear box and connected to the oil supply by lines that extend through an outer casing of the gear box. Thus, an off-line filter may be operated independently from operation of the primary oil circulation system. An advantage of such an off-line system is that it may allow the oil filter to be active even if the primary oil circulation system is not active. In addition, it may provide for relatively easy modification and/or servicing of the oil filter. Another advantage of such an off-line filter system is that it may be easily retrofitted to, i.e., added to, a gear box that was not originally outfitted with (or requires an additional) oil filter. However, the requirement of a secondary oil pump may increase cost and/or servicing requirements.
In contrast, an in-line filter system is operatively disposed along the flow path of the primary oil circulation system. As oil is pumped by the primary oil pump, the oil is filtered as part of the primary oil circulation system driven by the primary oil pump. Thus, an in-line filter is active whenever the primary oil pump is operating. An advantage of an in-line system is that it often provides a more compact and/or easier to install gear drive. Another advantage of an in-line system is that a secondary oil pump is not required. However, adding and/or servicing the filter of such an in-line system in the field, in particular when arranged as part of a gear drive for a dry cooling system and/or a steam condenser without an originally installed filter, can be highly labor intensive and/or cost prohibitive.